If you're feeling stuck in a life rut, it may be easier than you think to get out of it. Three simple steps to get your happy self back:

Do just one thing. "Studies suggest that only ten percent of our happiness is due to our circumstances -- people often think it's more --  while forty percent is a result of actions we take," says Steven Toepfer, Ph.D., an assistant professor of family studies at Kent State University in Salem, OH. (The other half is explained by genetics.) Today, take action for you: Go for a walk, call a friend, or make a reservation for a date-night dinner (call a sitter, too).

Write a letter. In a new study measuring how gratitude affects happiness, Toepfer had participants compose short notes to three people who had influenced them. The result: The letter writers got happier. It feels good to connect, he explains. Or write to your future big kid. "It'll help you see that the early, hard days are finite," he says.

Be realistic. No one is happy every day. When you're feeling down, think of one fun thing you're proud of -- your witty Facebook postings, your DIY manicures, your killer cupcakes -- to put a smile back on your face.